Elastography has been under development during the last decade and is recognized as having great potential as an emerging major tool for breast and prostate cancer diagnosis. It may also play an important role in other areas such as monitoring tumor ablation therapy and intravascular plaque classification. Initial clinical trials are under way and there is a great need for temporally stable heterogeneous phantoms to enable vigorous development of elastographic hardware and software. The overall objective of this grant is to develop tissue-mimicking (TM) materials and phantoms with long-term stability of elastic, ultrasonic and MR properties. These materials are to be used for developing and performance testing of elastography (elastic imaging) systems. One type of phantom will be used in calibration, standardization and performance assessment of elastography machines and the various algorithms used to create elastograms. Another type of phantom will be used to assess the accuracy of an instrument (Nanolndentor XP(R)) dedicated to in vitro mm-scale mapping of the Young's modulus for thin slices of normal and abnormal tissue specimens. A third type will consist of anthropomorphic phantoms with precisely known geometries and physical properties. These will be made in order to allow a more realistic challenge to elastographic systems under development; such phantoms will include breast and prostate relative to cancer diagnosis and other organs such as the liver regarding tumor ablation. Long-term stability of newly developed materials and heterogeneous phantoms will be completed by monitoring elastic, ultrasonic and MR properties and internal structural configurations of heterogeneous phantoms. Refined heterogeneous performance phantoms and anthropomorphic phantoms will be developed iteratively with assessments and advice from collaborators who are active researchers in ultrasound and MR elastography.